The present invention relates to removing hair with periodically applied heat without damaging the skin.
The removal of unwanted hair from the body can be accomplished with non-mechanized means, for example razors, tweezers or wax, all of which are uncomfortable to use, irritate the skin and/or cause damage to the skin.
Mechanized cutting means for cutting hair, for example dry shavers, in addition to being uncomfortable to use, are limited to cutting hair of a specific length. Beard trimmers, for example, cut facial hair stubble, but cannot cut longer hairs on the scalp.
Alternate devices that use an electrical or electromagnetic source, for example electrolysis and photothermolysis, are effective but usually require an experienced operator to ensure proper administration without untoward side effects.
The use of heated wires or other structures to cut hair from a skin surface has been proposed. However, a heat generator that generates heat of a sufficient magnitude to cut hair and that cuts the hair close to the skin, often damages the skin. Alternatively, since the heat generator is offset from the skin to prevent skin damage, unwanted stubble is left behind.
In Peterson, U.S. Pat. No. 3,934,115, parallel metal strips on the upper side of a ceramic facing that contacts the skin, are used to cut hair. Hills, in U.S. Pat. No. 2,727,132 and P. Massimo in IT 1201364, use a continuously heated element to burn hair. P. M. Bell in U.S. Pat. No. 558,465, D. Seide in U.S. Pat. No. 589,445, G. S. Hills in U.S. Pat. No. 2,727,132, G. L. Johnson in U.S. Pat. No. 3,093,724, Hashimoto in U.S. Pat. No. 5,064,993 and U.S. Pat. No. 6,307,181 B1, F. Solvinto in FR 2531655 and EP 0201189, and E. Michit in FR 2612381, use a continuously heated wire to burn hair. J. F. Carter in U.S. Pat. No. 3,474,224, provides a circular comb device for burning nose hairs. Aside from physically separating the skin from the heated element, these references do not appear to provide other protection against burning of the skin.
Vrtaric in U.S. Pat. No. 4,254,324, provides a heat hair cutting system that is applied only to the tips of the hair to remove the split ends.
A prior art system for depilation, based upon photothermolysis is shown in U.S. Pat. No. 6,187,001, the disclosure of which is incorporated by reference. In this method, radiant energy is used to heat the air surrounding the skin to remove hair. EP publications EP 0 736 308 and EP 0 788 814, the disclosures of which are incorporated herein by reference, utilize radiant energy to selectively heat the hair, destroying it.
According to an aspect of some embodiments of the present invention, a device comprises a heat generator that generates continuous heat of sufficient temperature to cut hair while contacting the skin. However, during the process of cutting hair, the heat generator is prevented from damaging the skin by controlling the period of time during which heat continuously contacts a given area of skin. In some embodiments of the present invention, a heat generator continually contacts the skin and the period of its heat generation is limited to prevent skin damage. In some embodiments of the present invention, the generator remains hot throughout its duty cycle and is removed from contacting a section of skin to limit the period of time in which heat is applied, thereby preventing skin damage.
According to an aspect of some embodiments of the present invention, pulsed heat is applied through a heat generator containing one or more heat elements that contact the skin at least intermittently. In an exemplary embodiment, a pulsed heat generator provides pulsed heat at the heat elements wherein the pulses of heat are short enough so that although the temperature is high, the amount of heat transferred to the skin does not damage the skin. On the other hand, hair that contacts the heat element is destroyed, due to the lower heat capacity of the hair. Such a device may contact the skin substantially continuously.
As used herein, a heat generator is defined as a unit containing one or more heat elements heated to a temperature sufficient to cut hair during a given period of time in which it is in contact with the hair. It should be understood that current applied to the heat element at the line frequency (50-60 Hz) is to be considered continuous current, since it provides substantially constant heat.
Unless specified, further embodiments apply to both pulsed heating aspects and non-pulsed heating aspects of the present invention. Furthermore, while either pulsed or continuous heating may be described in reference to an embodiment of the invention, pulsed heating is generally usable in all the embodiments that are described with continuous heating. Additionally, embodiments that are described as using pulsed heating can use continuous heating if means for avoiding overheating of the skin as described herein are provided.
The cutting of a hair is dependent upon the magnitude of heat absorbed by the hair, whether a low temperature over a long period of time or a high temperature over a short period of time, whether pulsed or non-pulsed heat. Hence, the heat generator may generate heat at a lower temperature for a longer period of time or at a higher temperature for a shorter period of time in order to cut hair.
Heat builds in a specific area of a given hair and reaches a sufficient magnitude to cut the hair substantially independent of the hair length. In an exemplary embodiment of the present invention, a single apparatus cuts hair of a variety of lengths, from facial stubble to long hair on the scalp, in a variety of persons. Additionally or alternatively, the present invention allows a single apparatus to cut hair of a variety of lengths without exchanging, for example, cutter accessories. Further, the heat element used to cut hair, provides a sterile cutting environment, preventing the transmittal, for example, of scalp bacteria from one user to the next.
In some embodiments of the present invention, a heat generator provides heat of sufficient temperature to cause cessation of hair regrowth through destroying a hair growth regulatory mechanism as identified by R. L. Rusting in xe2x80x9cHairxe2x80x94Why it grows, Why it stopsxe2x80x9d, Scientific American 248:6 June 2001, pp. 56-63. Alternatively, a heat generator provides heat at a lower magnitude to cause delay of hair regrowth through partial destruction of the hair growth regulatory mechanism.
In an exemplary embodiment of the invention, the heat generator contains one or more heat elements, for example a heated wire and/or heated strip that contacts the hair and, optionally, the skin. Additionally or alternatively, the one or more heat elements consist of one or more of a wire, a ribbon, or a conductive coating on a non-conductive surface, for example a ceramic material in the form of a bar. Optionally, the one or more heat elements contain, at least in part, a metal. Alternatively, they do not contain any metal.
In other embodiments of the invention, the heat generator comprises two or more heat elements. The hair is cut, for example, with absorption of an appropriate amount of cumulative heat by each hair. Two or more heat elements promote faster transfer of the necessary cumulative heat than, for example one heat element, allowing faster movement of the unit while cutting the hair.
Additionally or alternatively, two or more heat elements allow each heat element in the heat generator to maintain a lower temperature while cutting hair as compared to a heat generator with a single heat element at a higher temperature.
Additionally or alternatively, the pulsed current is pulsed at different times through the two or more heat elements and is, for example, synchronized so that one heat element generates heat while another heat element does not generate heat or, optionally, generates heat at a lower temperature.
Optionally, the heat generator comprises one or more walls that are perpendicular to the skin comprising, for example, a slot through which hair passes. In an exemplary embodiment, the one or more heat elements are moved by the device in relationship to the slot during use to prevent damage from heat buildup in a given area of skin. For example, in some embodiments of the invention, the heat generator, or a portion of the heat generator, is mechanized to be periodically removed from an area of skin. The heat generator, for example lifts the one or more heat elements from the skin in a regular cycle or by moving them along the surface of the skin. When a mechanized heat generator contains two or more heat elements, the heat elements, for example, have an axis parallel to the skin and rotate around the axis that is parallel to the skin.
In an alternative mechanical embodiment, the mechanization provides for rotation of the heat elements about an axis perpendicular to the skin, such that the heat element moves along the surface of the skin. This provides for contact times with the skin that do not cause skin burns while providing for continuous cutting action, since all of the heat elements are adjacent to the skin with a high duty factor.
In some embodiments of the present invention, two or more heat elements are situated on a vertical plane in relationship to the skin surface, so that the hairs are cut successively closer to the skin as the heat elements sequentially pass an area of skin. Alternatively or additionally, the heat generator comprises two or more heat elements situated on a horizontal plane to the skin so that cumulative heat appropriate for cutting a hair may be provided sequentially as the multiple heat elements pass the same site.
In an exemplary embodiment, the heat generator comprises two or more heat elements of different cross sectional sizes, with the heat element of greater cross section providing greater transfer of heat to cut hair while at the same temperature as the heat element of lesser cross section. Optionally, heat elements of different cross sectional sizes are located in a cylinder about an axis that moves perpendicular to the skin. Additionally or alternatively, the heat elements of different cross sectional sizes are situated in a non-vertical plane in relationship to the skin with one heat element at a different height from the skin than another heat element. For example the thicker heat element is located further from the skin to provide faster coarse cutting of the hair. Additionally or alternatively, the heat elements of different cross sectional sizes are situated on a horizontal plane in relation to the skin with one behind the other. For example, the thicker heat element is located in front of the thinner heat element, so the thinner heat element is used to cut the relatively fewer hairs that may have been left uncut the larger first heat element.
Similarly, heat elements of different cross sectional sizes that are arranged in a cylinder or on a horizontal or non-horizontal plane, allow the thicker heat element to cut the bulk of the hairs in its path while the thinner heat element cuts the relatively few hairs missed by the first heat element.
In an exemplary embodiment, the heat generator cuts hair in conjunction with a cooling apparatus, for example a fan, to provide cooling to the skin during the cutting process. In addition, when pulsed heating is used, the fan helps to remove heat from the heat element during the xe2x80x9coffxe2x80x9d time, so that a higher repetition rate for the heat pulses and a higher duty cycle can be used.
In an exemplary embodiment, the hair cutting apparatus includes a grasping structure designed to be grasped by an operator to which the heat generator is attached. The heat generator is held by the grasping structure at a specific angle to the skin, for example, perpendicular to the skin. Optionally, the heat generator is held at a non-perpendicular angle to the skin. The angle of heat generator, whether perpendicular or non-perpendicular is varied, for example, according to the design of the grasper.
In an exemplary embodiment, one or more posts provide the connection between the grasping structure and the heat generator. These posts are, for example, flexible or spring loaded so that as the heat generator moves across the contour of the skin, the heat generator moves up and down and/or swivels on the flexible posts in relation to the grasper. This movement prevents, for example, the heat element from pressing with undue force into the skin surface, causing skin damage.
In an exemplary embodiment of the present invention, heat is applied through a heat element that contacts the skin while two or more skin depressors located in proximity to the heat elements hold the skin flat. The two or more skin depressors prevent the heat element from sinking into the skin and causing skin damage due to increased contact area between the skin and the heat element. Optionally, one or more rows of skin depressors touch the skin and the one or more heat elements are parallel to the one or more rows of skin depressors. Additionally or alternatively, two rows of skin depressors are provided and the one or more heat elements are located between the two rows of skin depressors, optionally parallel to the two rows of skin depressors. Optionally, the one or more heat elements are not parallel to the two rows of skin depressors.
In an exemplary embodiment, the one or more heat elements of the heat generator are held at one or both ends by a tension generator. The one or more tension generators comprise, for example, a spring-loaded mechanism, to tighten the one or more heat elements of the heat generator during longitudinal expansion that may occur during heat generation. Additionally or alternatively, said one or more tension generators tighten the one or more heat elements to prevent substantial deformation while pressing against hair during hair cutting.
In an exemplary embodiment of the present invention, the one or more skin depressors are designed so that the one or more tension generators do not cause skin damage during cutting. For example, the one or more skin depressors located near the tension generator protrude beyond the tension generator so the skin does not contact the tension generator, thereby preventing buildup of heat and resultant skin damage.
Additionally or alternatively, the one or more rows of skin depressors provide a cooling mechanism for the heat elements. As the pressure on the heat elements of the heat generator, caused by the hairs in its path, increases, the heat elements of the heat generator displace and touch one or more of the skin depressors and cool. This cooling of the heat elements of the heat generator prevents heat buildup that can cause damage to the skin. A second pass cuts the hairs in the path of the cooled heat generator that were not cut during a first pass.
Optionally, the one or more rows of skin depressors provide current to the one or more heat elements of the heat generator only when the heat generator is in motion. In an exemplary embodiment the heat elements contain, for example, a positive charge potential and the two or more rows of skin depressors are connected to an electrical ground. As the heat generator is moved along the skin and comes against hairs in its path, the cool heat elements remain stationary against the hairs. As the heat generator continues motion, the heat elements bend and touch a row of skin depressors, thereby completing the circuit so electricity flows through the heat elements to the grounded skin depressors and the elements heat up. Upon cessation of motion, the heat elements no longer press against hairs in their path and become straight, for example with the assistance of the tension generated by the tension generator, so they no longer touch a row of skin depressors. The current through the heat elements is thereby disrupted and the heat elements cool.
In an exemplary embodiment, heat is applied through a heat element controlled by a motion detector so the heat element provides heat only while the heat element moves in relation to the skin. Upon slowing of the heat generator""s motion below a specific rate, or its cessation of motion, the motion detector stops the production of heat by the heat element. Additionally or alternatively, in response to reduction or cessation of motion, the temperature of heat, produced by the heat generator, is reduced.
In an exemplary embodiment, the temperature and (when a pulsed heat source is used) pulse rate, and/or pulse width in a single heat element is controlled by a velocity detector. One or more of these factors is raised or lowered responsive to the velocity of the heat generator. This control, for example, prevents damage to the skin by excessive heat at a lower velocity. Additionally or alternatively, a velocity detector controls one or more factors of temperature, pulse rate and/or pulse width in each heat element individually when there are, for example, two or more heat elements.
In an embodiment of the pulsed aspect of the present invention, the pulsed heat generator applies continuous current as it moves at a higher speed in relation to the skin and applies pulsed current optionally at a rate that is reduced as the heat generator moves at a lower speed.
There is thus provided a hair cutting apparatus comprising a structure, a portion of which being adapted for placement against a skin surface where hair is to be cut, a heat generator comprising one or more heat elements heated to a temperature sufficient to cut hair, at least one of said heat elements being juxtaposed with said portion and positioned to touch said skin and a controller that controls said heat generator to prevent heat from being applied continuously in a single area for sufficient time to cause skin damage.
Optionally said controller comprises a velocity detector and the velocity detector causes said heat generator to increase the temperature of said heat element when the velocity of said apparatus increases in relation to said skin and to decrease the temperature of said heat element when the velocity of said apparatus decreases in relation to said skin.
In an embodiment of the present invention, said heat generator provides pulsed heating of said one or more heat elements. Optionally, the one or more heat elements are heated for a period of between 10 and 100 msec for each on-off cycle. Optionally, the heating of the heat element is repeated at a pulse repetition rate of 1-100 Hz.
In an exemplary embodiment, said controller comprises a velocity detector. Optionally, the velocity detector causes said heat generator to increase its rate of repeated pulsing when the velocity of said apparatus increases in relation to said skin and to decrease its rate of repeated pulsing when the velocity of said apparatus decreases in relation to said skin.
Optionally, the velocity detector causes said heat generator to increase the width of each pulsation during said repeated pulsing when the velocity of said apparatus increases in relation to said skin and to decrease the width of each pulsation during said repeated pulsing when the velocity of said apparatus decreases in relation to said skin.
Optionally, the velocity detector causes said heat generator to generate continuous heating when the velocity increases above a specified velocity as sensed by said velocity detector. Additionally or alternatively, the velocity detector causes said heat generator to increase the temperature of said heat element when the velocity of said apparatus increases in relation to said skin and to decrease the temperature of said heat element when the velocity of said apparatus decreases in relation to said skin.
In an exemplary embodiment, said velocity detector comprises an optical velocity detector. Optionally, said velocity detector comprises a mechanical velocity detector.
In an exemplary embodiment, said controller comprises a motion detector. Optionally, the motion detector controls said heat generator, switching said heat generator on when said heat generator is in motion in relation to said skin and switching said heat generator off when said heat generator-is not in motion in relation to said skin. Additionally or alternatively, said motion detector comprises an optical motion detector. Optionally, said motion detector comprises a mechanical motion detector.
In an exemplary embodiment, the one or more heat elements comprise ribbon-shaped and a wide side of said ribbon-shaped heat elements are substantially perpendicular to said skin. Optionally, the one or more heat elements comprise a wire substantially parallel to said skin. Optionally, the one or more heat elements comprise two or more heat elements. Additionally or alternatively, a plane formed by the two or more heat elements is parallel to said skin. Optionally, the plane formed by the two or more heat elements is perpendicular to said skin. Optionally, the plane formed by the two or more heat elements is neither parallel nor perpendicular to said skin.
In an exemplary embodiment, the two or more heat elements have different cross-sectional areas. Optionally, the two or more heat elements have different cross-sectional configurations. Optionally, the heat applied by at least two of the two or more heat elements is applied at a different pulse rate. Optionally, the heat applied by at least two of the two or more heat elements is applied at a different pulse width or the temperature in at least two of the two or more heat elements is different.
In an exemplary embodiment of the present invention, at least one end of one heat element is attached to a tension generator. Optionally, the tension generator comprises a spring. Optionally, the tension generator comprises a spring-loaded wire. Additionally or alternatively, said portion that is adapted for placement against the skin comprises two or more skin depressors that contact said skin surface. Optionally said two or more skin depressors are perpendicular to said skin.
Optionally, said two or more skin depressors comprise one or more rows of skin depressing elements.
In an exemplary embodiment, said two or more skin depressors comprise at least two rows of skin depressing elements. Optionally, said two or more skin depressors comprise two parallel rows of skin depressing elements. Optionally, said one or more heat elements are located between said two rows of skin depressing elements.
Additionally or alternatively, at least one heat element is parallel to one or more rows of skin depressing elements. Optionally, said at least one heat element is not parallel to one or more rows of skin depressing elements. Alternatively, said at least one heat element is not parallel to said two or more rows of skin depressing elements. Optionally, at least one end of one heat element is connected to a tension generator and one or more of said skin depressing elements protrude beyond said tension generator.
In an exemplary embodiment, when the at least one heat element is so constructed that when it contacts one or more hairs during motion, it displaces opposite its direction of motion in relation to the skin. Optionally, when said heat element displaces in an amount sufficient to contact one of said skin depressors, it cools as it contacts the skin depressors. Optionally, when said heat element displaces in an amount sufficient to contact one of said skin depressors, it heats as it contacts the skin depressors.
In an exemplary embodiment, said portion adapted for placement against a skin surface is separate from said structure and said portion is mounted with one or more mountings on said structure. Optionally, said mounting comprises flexible posts. Additionally or alternatively, said mounting comprises spring-loaded mountings. Additionally or alternatively, said mountings are electrically connected to said heat elements.
In an exemplary embodiment, the controller comprises a motor that moves the heat elements along the skin, so that the temperature of the skin does not rise to a level that causes it to burn. Optionally, the heat elements are elongate heat elements arranged to form a discontinuous cylindrical surface having a rotation axis. Additionally or alternatively the heat elements rotate about the axis they are periodically brought into contact with and removed from contacting said skin surface. Optionally, the axes of the heat elements radiate from an axis, said axis being perpendicular to the axes of the heat elements. Optionally, the controller rotates the elongate heat elements about the axis.
In an exemplary embodiment, said apparatus includes a fan that provides cooling for at least one heat element.
There is thus further provided a method of cutting hair comprising providing a heat element touching the skin, said heat element being heated to a peak temperature high enough to cause the cutting of hair and the burning of skin at said position and interrupting the heating of the skin at said position before the skin is burned. Optionally, said interrupting comprises interrupting a supply of heat to the heat element. Optionally, said interrupting is accomplished by a motion detector when it detects a lack of motion of said hair cutting apparatus in relation to said skin.
In an exemplary embodiment, interrupting is accomplished by a velocity detector when it detects a reduction in velocity of said heat element in relation to said skin. Additionally or alternatively, interrupting comprises moving the heat element along the skin so that it does not remain in a position to bum the skin for a time sufficient to burn the skin.